Small molecule-induced epigenomic reprogramming of APL blasts leading to antiviral-like response and c-MYC downregulation.

Acute promyelocytic leukemia (APL) is an aggressive subtype of acute myeloid leukemia (AML) in which the PML/RARα fusion protein exerts oncogenic activities by recruiting repressive complexes to the promoter of specific target genes. Other epigenetic perturbations, as alterations of histone H3 lysine 9 trimethylation (H3K9me3), have been frequently found in AMLs and are associated with leukemogenesis and leukemia progression. Here, we characterized the epigenomic effects of maltonis, a novel maltol-derived molecule, in APL cells. We demonstrate that maltonis treatments induce a profound remodulation of the histone code, reducing global H3K9me3 signal and modulating other histone post-translational modifications. Transcriptomic and epigenomic analyses revealed that maltonis exposure induces changes of genes expression associated with a genomic redistribution of histone H3 lysine 4 trimethylation (H3K4me3) and lysine 27 acetylation (H3K27ac). Upregulation of interferon alpha and gamma response and downregulation of c-MYC target genes, in function of c-MYC reduced expression (monitored in all the hematopoietic neoplasms tested), represent the most significant modulated pathways. These data demonstrate the ability of maltonis to epigenetically reprogram the gene expression profile of APL cells, inducing an intriguing antiviral-like response, concomitantly with the downregulation of c-MYC-related pathways, thus making it an attractive candidate for antileukemic therapy.

Playing with Structural Parameters: Synthesis and Characterization of Two New Maltol-Based Ligands with Binding and Antineoplastic Properties.

Two maltol-based ligands, N,N'-bis((3-hydroxy-4-pyron-2-yl)methyl)-1,4-piperazine (L1) and N,N',N'-tris((3-hydroxy-4-pyron-2-yl)methyl)-N-methylethylendiamine (L2), were synthesized and characterized. L1 and L2, containing, respectively, two and three maltol units spaced by a diamine fragment, were designed to evaluate how biological and binding features are affected by structural modifications of the parent compound malten. The acid-base behavior and the binding properties towards transition, alkaline-earth (AE) and rare-earth (RE) cations in aqueous solution, studied by potentiometric, UV-Vis and NMR analysis, are reported along with biological studies on DNA and leukemia cells. Both ligands form stable complexes with Cu(II), Zn(II) and Co(II) that were studied as metallo-receptors for AE and RE at neutral pH. L1 complexes are more affected than L2 ones by hard cations, the L1-Cu(II) system being deeply affected by RE. The structural modifications altered the mechanism of action: L1 partially maintains the ability to induce structural alterations of DNA, while L2 provokes single strand (nicks) and to a lesser extent double strand breaks of DNA.

PdII and PtII complexes with a thio-aza macrocycle ligand containing an intercalating fragment: Structural and antitumor activity studies.

Two new PtII and PdII complexes of formula [LMCl2] (M=Pt, Pd) were synthesized and characterized both in solution and solid state. They were obtained using the thio-aza macrocycle 9,18-dimethyl-12,17dithia-9,18,27,28-tetraaaza-29-oxatetracyclo[24.2.1.02,7.020,25]enneicosa-2,4,6,20,22,24,26,281-octaene (L) containing the 2,5-diphenyl [1, 3, 4]oxadiazole as intercalating fragment. MII is coordinated in cis-position by the two S atoms of L. The two crystal structures of [LPtCl2] and [LPdCl2] complexes showed that the MII ion is located outside the macrocyclic cavity. The square planar coordination sphere is fulfilled by two chloride anions in a cisplatin-like arrangement with the chloride leaving groups exposed to the environment. The biological activity of both [LPtCl2] and [LPdCl2], monitored towards a leukemic cellular model (U937), is coherent with their ability to interfere, at different levels, with the DNA structure.

Synthesis, basicity, structural characterization, and biochemical properties of two [(3-hydroxy-4-pyron-2-yl)methyl]amine derivatives showing antineoplastic features.

The N,N'-bis[(3-hydroxy-4-pyron-2-yl)methyl]-N,N'-dimethylethylendiamine (malten) and 4,10-bis[(3-hydroxy-4-pyron-2-yl)methyl]-1,7-dimethyl-1,4,7,10-tetraazacyclododecane (maltonis) were synthesized and characterized. The acid-base behavior, structural characterizations, and biochemical studies in aqueous solution were reported. Each compound contains two 3-hydroxy-2-methyl-4-pyrone units (maltol) symmetrically spaced by a polyamine fragment, the 1,4-dimethylethylendiamine (malten), or the 1,7-dimethyl-1,4,7,10-tetraazacyclododecane (maltonis). They are present at physiological pH 7.4 in the form of differently charged species: neutral but in a zwitterion form for malten and monopositive with an internal separation of charges for maltonis. Malten and maltonis are both able to alter the chromatin structure inducing the covalent binding of genomic DNA with proteins, a feature consistent with the known antiproliferative activity exerted by this class of molecules. Solid-state results and MD simulations in water show that malten, because of its molecular topology, should be more prone than maltonis to act as a donor of H-bonds in intermolecular contacts, thus it should give a better noncovalent approach with the negatively charged DNA. Crystal structures of [H(2)malten](2+) and [H(2)maltonis](2+) cations were also reported.

Synthesis of a large amino-phenolic cage. Synthesis, crystal structures, and acid-base and coordination behavior toward cations and anions.

The synthesis and characterization of the new polyaza-phenolic-macrobicycle 32-hydroxy-1,4,7,10,13,16,19,22-octaazatricyclo-[11.11.7.1(26,30)]-diatriconta-26,28,Delta(30,32)-triene (L) are reported. L incorporates a 2,6-dimethyl-phenolic unit bridging two opposite amine functions of the [24]aneN(8) polyazamacrocyclic base to obtain a large cage. The basicity and binding properties of L toward Cu(II), Zn(II), and Cl(-) were determined by means of potentiometric measurements in aqueous solution (298.1 +/- 0.1 K, I = 0.15 mol dm(-3)). L can add up to six acidic protons, yielding the H(5)L(5+) species or the H(6)L(6+) species, depending on the ionic medium used. The molecular topology of L permits the formation of a highly positive three-dimensional cavity in the polyprotonated species that is able to host the chloride anion. This was detected both using potentiometric data, log K = 41.33 for the reaction L + 6H(+) + Cl(-) = H(6)LCl(5+), and in (35)Cl NMR experiments that showed interactions also with the H(5)L(5+) and H(4)L(4+) species. The anion is probably hosted inside the three-dimensional cavity of L, and stabilized by H-bonding interactions with the ammonium groups, as depicted in the crystal structure of the H(6)L(6+) cation reported. L forms mono- and dinuclear complexes with all the metal ions investigated; the dinuclear species are the only existing species with an L:M(II) molar ratio of 1:2 at pH higher than 6. The phenolate oxygen atom coordinates the two metal ions in a bridged disposition, drawing them inside the macrobicyclic cavity. The two metals were found to be quite isolated by the medium, and were coordinated by all the amine groups of L, as shown by the crystal structure of the dinuclear [Zn(2)H(-1)L](3+) species. This species can bind guests such as hydroxide and phosphate anions. Studies of anion binding in aqueous solution using pyrochatecol violet as the sensing guest revealed that the [Zn(2)H(-1)L](3+) species is able to bind one phosphate at physiological pH.

Dinuclear copper(II) complex as nitric oxide scavenger in a stimulated murine macrophage model.

Nitric oxide is a gaseous, short-living free radical which behaves as an important signaling molecule with pleiotropic capacities including vasodilatation, neurotransmission, and microbial and tumor cell killing, as well as in tissue damage and organ-specific autoimmune disorders. Here, a synthesized, dinuclear copper complex system in vitro obtained by the simple aza-phenolic ligand 2,6-bis[[bis-(2-aminoethyl)amino]methyl]phenol (L) and Cu(II) ion has been used. The stability constants of ligand L with Cu(II) ion were determined through potentiometric measurements in aqueous solution (37.1 +/- 0.1 degrees C, I = 0.15 M of NaCl) to mimic the biological medium. The measurements demonstrated that [Cu(2)H(-1)L(OH)](2+) (DCu) is the predominant species present in solution at pH 7.4. The molecular structure of the ligand in this species permits the cooperation of the two copper ions in assembling the substrate, thus the complex can be used as a receptor for small molecules such as NO. As a biological model, we chose the production of NO catalyzed by inducible nitric oxide synthase obtained from RAW 264.7 murine macrophage cell line stimulated with LPS, which enabled us to prove that NO is coordinated by the DCu complex, modifying its EPR spectra. The coordination of NO with DCu reduces the level of nitrite in the culture medium of stimulated RAW 264.7 macrophages without any inhibition in the expression of iNOS.